EFI Fuel Delivery: Knowing What You Need Is Key To Smooth Running

As much as we hate to admit it, upgrades that involve electronics are intimidating to many enthusiasts. There are a lot of guys that have no hesitation when it comes time to rebuild a suspension or an engine, but electronics are often avoided. One of the more intimidating upgrades has to with installing electronic fuel injection systems. It’s not that enthusiasts are afraid of enhanced throttle response, improved fuel efficiency, and better overall performance – all things associated with EFI – it just comes down to knowledge. The less we know about something, the more we are afraid of it.

It’s impossible to logically argue the benefits of EFI, but the wiring and fuel system modifications needed, make many enthusiasts cling to carburetors. That’s not a bad thing, as carburetors have been around forever – and they do work. But in recent years, aftermarket companies have begun to take the hassle out of EFI swaps by developing more easily tuned systems that require less of a degree in electrical engineering.

Many EFI systems available come with a basic fuel delivery system. But, there is an inherent problem that can still cause issues after the swap is complete – fuel slosh.

But, there is an aspect of upgrading to EFI that many seem to forget about – the delivery of the fuel to the EFI system mounted to the engine. The many self-learning EFI kits found on the market today are all quality engineered systems, and they even come with a basic EFI-capable fuel system to get your car running. But, although they are adequate in regard to supplying fuel to the engine, one thing that seems to get overlooked is getting the fuel out of the tank under any condition.

As great as an EFI upgrade is for your car, the issue of fuel slosh in your tank can cause unwanted “hiccups” during daily operation. This crude diagram shows what can happen to fuel when the tank gets low. Starting and stopping in traffic can cause the fuel to move (slosh) back and forth in the tank and uncover the fuel pickup.

What’s The Problem?

When your car or truck was running a carburetor, if the tank was low on fuel, the subsequent fuel slosh that occurred while stopping or initiating vehicle movement which uncovered the fuel pickup, was not an issue. That is because, if the fuel tank got low and fuel slosh caused the fuel-pickup tube to temporarily become “un-submerged,” the carburetor’s fuel bowl carried a small reserve of fuel that would continue to feed the engine. Even if the fuel pickup is uncovered, the engine’s vacuum could still pull fuel from the carburetor’s fuel bowl. But, in an EFI situation, the results are drastically different.

During that same fuel-slosh scenario, there is no “reserve” fuel supply. The EFI system relies on constant pressure supplying fuel from the tank. If the pickup tube is not fully submerged in fuel – even for a brief moment – the EFI pump will suck air. That is noticed by you when the engine stumbles – or worse – stalls. Many enthusiasts have experienced this situation, and we decided to put together a quick guide to show you that there are options to help combat this frustrating occurrence.

The self-learning EFI market has given enthusiasts a quick and easy way to upgrade their car's engine. But, it doesn't matter what EFI system you use, if it doesn't get sufficient fuel, it will not work properly.

To do that, we reached out to the folks at Edelbrock, FiTech EFI, and Holley. All three companies offer fuel-delivery products that can help your classic car or truck’s non-baffled tank keep your engine continuously fed.

We will focus on three fuel-delivery variations you can use to upgrade your fuel system. One is a sump tank, another is an in-tank upgrade, and the last one outlines fuel tank replacement options.

Let’s Start With Easy

One of the easiest fuel-system upgrades to compliment an EFI system is an external sump tank. FiTech’s HyperFuel line has what it calls the Fuel Command Center 2 (FCC2). This unit is designed to be used in vehicles still using stock fuel tanks, but, have converted from using a carburetor to EFI. The Fuel Command Center 2 mounts under your hood, and your engine’s mechanical fuel pump feeds the FCC2. A 340-lph high-pressure pump is submerged inside the unit to feed high-pressure fuel to the EFI. This sump will always have a fuel reserve, and avoid fuel starvation caused by fuel slosh.

The Command Center 2 is designed for the guy that is still using a low-pressure fuel system, and has either updated to EFI, or has installed a late-model engine under the hood.

“Our sump kits (Fuel Command Center 2 and G-Surge) are designed to be used with vehicles that have their existing mechanical or low-PSI electric pump still in use. They are designed to help vehicles with fuel starvation issues when being used in extreme lateral G-force environments or in off-road environments where severe angles are encountered,” said Mike Wahl of FiTech.

Edelbrock’s sump kit is for the guy wanting to feed an EFI system, but not modify his existing fuel system in the car.

Edelbrock’s Universal EFI Sump kit is also designed to provide the necessary high-pressure fuel required for EFI applications in vehicles still using a mechanical fuel pump. This is a complete self-contained system that can be easily installed under the hood. This is also available in either a 67 or 105-gph delivery capacity. It’s unique design allows it to deliver a constant fuel pressure with no fuel return line, external fuel pressure regulator, or fuel tank modifications. It is compatible with the existing factory fuel tank and fuel pump. “The Universal Fuel Sump is perfect for use in cars with engine swaps and/or those with aftermarket carb-to-EFI upgrades,” said Eric Blakely of Edelbrock.

In-Tank Upgrades

If you are looking to keep a sanitary look under your hood, and a sump tank is not an option for you, then we need to look at updating and/or modifying your car’s existing fuel tank. Upgrading the tank can be done multiple ways, and the path chosen is simply a matter of personal preference. For instance, if you are looking for a quick and easy way to upgrade, Holley Performance’s HydraMat is an easy solution to combat fuel slosh.

Holley’s HydraMat is an easy-to-install solution for combating fuel starvation during fuel slosh.

“HydraMat is a fuel reservoir/retention system that is inserted into the fuel tank or fuel cell, and then connected to the factory fuel pickup tube,” according to Jeff Teel of Holley Performance. It is designed to reduce fuel starvation issues present in hard cornering, acceleration, stopping, inclines, and low fuel conditions. Surface tension and fluid wicking are the secrets of the HydraMat. It has the amazing ability to draw from nearly any area that has contact with fuel and then store it in its internal reservoir. As any area of the HydraMat is uncovered, the tiny pores of the media are sealed by surface tension, forcing fuel to be contained in the reservoir and drawn from other areas of the mat where fuel is still available. The sheer size and coverage area of the HydraMat allows it to pull fuel from virtually any area in the tank or cell, eliminating the need for specialty reservoirs and pickup pumps.

HydraMat comes in various sizes and shapes to accommodate different tank sizes and openings. Square, rectangular, and “X” shaped mats are available to provide easy installation thru various sending unit access holes or fuel cell cover plates.

In-Tank Pump/Sending Units

Tank mounted fuel delivery units have been around for a while now. There are some that are drop-in, and some that require you modify your existing or new fuel tank. FiTech and Holley both have units that work well, but require some tank modifications. If you do not want to modify your tank, Holley offers OE-style fuel tank modules that are designed as a direct replacement for your factory pick-up and sending unit.

Holley’s part number 12-303 is an OE-style sending-unit assembly for 1968-72 Chevelle, Malibu, GM A-Body, and El Camino, that incorporates an in-tank fuel pump and HydraMat.

There is no need for tank modifications, and you will not have to replace your fuel tank. You can even retain the factory fuel hard line, just connect the outlet of the pump module to the hard line on your vehicle with some EFI-rated fuel hose and hose clamps.

The HyperFuel Hy-Fuel Single Pump In-Tank Retrofit Kit can be used in a return or return-less system (with the use of the built in regulator). With the pump submerged in fuel, it will run quieter and last longer. Its adjustable pump height makes this an easy way to convert your existing or new fuel tank to an in-tank EFI fuel system.

If modifying your tank is not an issue, FiTech, and Holley both offer in-tank fuel pump systems. FiTech’s Hy-fuel single-pump system can be used as either a return-style or returnless system. It has an adjustable pump-height, and can be used in fuel tanks ranging in depth from 6 to 14 inches. It is suitable for use in cars with up to 800 horsepower.

Holley’s 255-lph Drop-In Retrofit EFI Fuel System w/Hydramat Supports up to 550 horsepower with EFI, or 700 when using a carburetor.

Holley’s Retrofit In-Tank Fuel Module will convert your factory tank or fuel cell to an in-tank EFI fuel system. The conversion is easily accomplished with basic tools, and requires no welding or fabrication. The billet aluminum module includes a billet pump hanger-bracket to control pump vibration while also providing a low-profile design to fit where space is limited. It can support up to 550 horsepower in EFI applications.

One thing we do want to mention, is when drop-in modules are installed, they will only supply fuel to the engine if the internal pump is submerged. In other words, fuel slosh might still be an issue unless the tank is baffled. If no baffles are utilized, think how an internal pump might work with a product like HydraMat attached to it?

EFI-Ready Fuel Tanks

Finally, we have the ultimate in EFI fuel delivery upgrades, and that’s an EFI-ready fuel tank. Sometimes, upgrading to an EFI-compatible fuel tank just makes sense. In these instances, you once again have choices – Holley, and FiTech.

Holley's EFI Conversion Fuel Tanks are a direct fit for your application-no modifications necessary. The kit includes the tank, a 4000-lph fuel pump, internal baffling, and a fuel level sender. The tank is powdercoated for corrosion resistance and great looks.

Fitech’s line of HyperFuel’s stamped steel reproduction fuel tanks require no modifications to mount. The tanks include baffling, sending unit, and a 340-lph fuel pump.

Holley’s EFI Conversion Fuel Tanks are a direct fit for your application, and require no modification for installation. The kit includes the tank, a 255-lph fuel pump, internal baffling, and a fuel-level sender. Theses tanks are powdercoated for corrosion resistance and great looks.

While each of these companies offer various options, knowing what will work best for your specific application is paramount. That is why calling Edelbrock,FiTech, or Holley to discuss your car’s fuel-delivery needs is highly recommended.

Article Sources

About the author

Randy Bolig

Randy Bolig has been working on cars and has been involved in the hobby ever since he bought his first car when he was only 14 years old. His passion for performance got him noticed by many locals, and he began helping them modify their vehicles.